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Re: Aerating Wine / Mead While Fermenting

I aerate at the beginning right before pitching yeast in mead and beer. The yeast take up the O2 for division and reproduction. Adding O2 after the initial stage can result in acetobacter formation which produces vinegar taste. That is why fermentation is done in a closed fermenter. Oak barrels allow some oxygen transfer as well as plastic buckets, but using the vessels for extended periods requires periodic attention and expertise.

Re: Aerating Wine / Mead While Fermenting

I've never heard of aerating while fermenting; conventional wisdom as beerbee said is that you want to aerate well when pitching the yeast, then keep oxygen away once fermentation starts to avoid both chemical oxidation of flavor compounds and growth of aerobic contaminating bacteria.

Some meadmakers do a periodic degassing during fermentation. The idea is to agitate the must in an oxygen-free environment to get dissolved CO2 to bubble out. As high dissolved CO2 is somewhat toxic to yeast, this is supposed to create a faster, more complete fermentation with a cleaner flavor profile. I've never degassed myself and have been darn pleased with my meads :-)

Re: Aerating Wine / Mead While Fermenting

Aeration before the yeast leave their respirative life cycle stage is important for full attenuation as beerbee notes, but really shouldn't be performed much past when the primary ferment has kicked off. Later on, oxygen contact will oxidize rather than oxygenate the beverage, leading to off-flavors and color changes... it takes the live yeast stripping the o2 from solution during reproduction to protect the mead. Acetobacter are required in addition to oxygen for acetic acid formation, so if you are effectively preventing fruit flies from entering (one of the functions of an airlock) but allowing oxygen to interact then you'll only get oxidation (still to be avoided).

Re: Aerating Wine / Mead While Fermenting

I've only just started my first batch of mead, so what follows is based on what I've read/been told by other folks. When in doubt, I'd say listen to Ben. His handle is Brewcat for a reason.

To (hopefully) add to what has already been said, a lot of people will aerate/oxigenate up to the 1/3 sugar break. That's the point where 1/3 of the available sugar has been used up by the yeast. You figure that out based on your original specific gravity (O.G.) reading. If you assume your mead will finish at 1.000, then 1/3 of the way through would mean that a S.G. reading of 1.067 would be your 1/3 sugar break.

The method I use is to just take my big long stirring spoon, put it on the side of my plastic bucket primary at the surface of the mead, and drive it to the bottom as fast as I can (trying not to splash it out of the bucket). I'll also stir it vigorously in one direction and then switch directions.

Any time you open up your primary fermenter (to take a SG reading or whatever), you would be well served to sanitize everything you touch, or might have come into contact with something non-sanitized. Anything that comes into contact with the mead, SANITIZE!!

I have a friend who has an aeration schedule that he adheres to pretty stringently. For the first 2-3 days he'll aerate it a lot, but then after that he leaves it to do its thing. And remember to transfer it to a secondary as gently as you can, so as to avoid putting any extra air into it... i.e. No splashing!

Hope this helps. Ben or Vance or whomever: correct anything I may have wrong. I'm still learning too.

Re: Aerating Wine / Mead While Fermenting

Originally Posted by Erik the Red

To (hopefully) add to what has already been said, a lot of people will aerate/oxigenate up to the 1/3 sugar break.

Why do they do this? I've made a bit of mead but am no expert. I aerate initially before adding my yeast...but that is all. My meads ferment to completion in a matter of two to three weeks (to the alcohol tolerance of the yeast or the total consumption of sugar...depending on design). To my thinking, it cannot speed up the fermentation process enough to matter.

Let me never fall into the vulgar mistake of dreaming that I am persecuted whenever I am contradicted. - Emerson

Re: Aerating Wine / Mead While Fermenting

Usually initial aeration (or even thorough aeration in starter preparation, if a starter is cultured) will get you to the finish line just fine. For very stressful musts, for example high gravity (like 1.120++) especially combined with low pH or nutrient levels, a perfectly-timed mid-primary aeration can help, though not as much as fixing the underlying issue in the latter two cases. In those cases I just make a healthy yeast starter, building up yeast cell counts in a sterile medium of unhopped beer wort and then decanting the spent wort off the beautiful tan yeastcake... they'll be fully nourished and have an enormous crop of young 'uns to help with the chores so to speak. Yeast, even wine yeast, is cultured in beer wort as it is nutritionally perfect for yeast health.

Degassing the primary a bit can reduce the carbonic acid, but I'm a believer in aiming the arrow well before loosing it rather than trying to put fans along its course to keep it on target . That just means proper yeast nutrition and health at pitching, having enough (but not too much!) nutrient in the must to see it through, quality ingredients, sanitary equipment and good transfer technique. That said, there's nothing wrong per se with mid-ferment interventions; just be sure of sanitary practices and that you are fixing a known problem with an effective action. An example might be old country wine recipes that tell you to rack every month for a year or whatever... racking has a purpose but it does not in and of itself improve wine; once the need is met, further racking harms mead (and causes loss of volume, an unpardonable foul if done without a goal in mind ).

Re-reading the OP, there is a reason for racking/degassing besides CO2 and that is hydrogen sulfide, other sulfur compounds and some other dissolved gasses that want to be dispersed. Agitation and/or racking (done carefully so as to not oxidize) causes these gases to leave solution which does improve a wine or mead, but time does that too. I never rack more than once to secondary and maybe a second in a few weeks once it's fallen clear if I don't want to age on lees. Other than that good technique and maybe a gentle degassing is all I usually do. There are a few yeast strains that are voluminous "burrito night" producers that definitely benefit from bulk aging and degassing so that doesn't make it into the glass.

Many people make great meads and wines different ways and there truly is no "right" way. I just happen to be a biology nerd who loves yeast culture, so that's how I approach mead too.

Re: Aerating Wine / Mead While Fermenting

Often intermediate aeration is done as part of a stepped nutrient feeding schedule done, as a poster above describes, up to about the 1/3 sugar break. I've experimented with stepped nutrient additions and/or intermediate aeration and I haven't noticed any significant benefit over just giving the must a good whisking or stir at the start and letting it run to completion. I know some people who swear by such techniques but I don't see (or taste) much difference. The times I have done it, I was making 1 gallon batches so it was easy to just pull off the airlock, cover the neck with my hand and invert the jug a few times. Pull hand off to add more air to the jug and repeat. With any larger fermenter, I would use a spoon, racking cane, stir plate or some other method. Keep in mind there will be gas dissolved in the must that will come out of solution when you do this and it will make a mess if you aren't careful.